The title of Stacie Passon’s new film “Concussion” is a bit of a misdirect. The eponymous baseball accident in the first five minutes of the film could well be the cause of everything that follows, but it could also be little more than an instigating incident–a fluke of life that separates what was before from what is now. It’s a testament to Passon’s subtle and somewhat conflicting film that it’s impossible to tell just what the concussion in “Concussion” really signifies.

Abby (Robin Weigert) is a housewife in the suburbs of New York with two kids, a divorce lawyer wife named Kate, and a comfortable life filled with equal parts spin class, yoga and ennui. When an errant ball thrown by Abby’s son at a baseball game lands her in the ER, she undergoes a journey of personal and sexual self-discovery.

But that phrase is a little too pat to address the complexities of this film. Abby, a sometime decorator, tells Kate at the hospital with an ice pack to her eye that she’s getting back to work; she soon buys a fixer-up loft in the city to remodel and flip. The apartment becomes the site of a series of secret trysts, where Abby goes from buyer–with a young woman recommended by Justin, the strapping young twentysomething who helps Abby with the remodel–to, well, seller, with Justin’s girlfriend finding the girls for Abby’s newfound “work.”

But while extramarital sex fuels the plot of “Concussion”–and there are a lot of excellent, sensitive and sometimes uncomfortable scenes of intimacy in the film–this sex is at heart an outward expression of the deeper lack of fulfillment that Abby struggles with. “Concussion” is really a film about middle age, monogamy and self-worth, and, of course, about sexuality and gender–the kind of sustained look that long-term, adult, queer relationships are so rarely given in film.

In its subject matter–and its unabashed sexuality–“Concussion” is a gutsy film, all the more so given its helmer, Stacie Passon, is a first-time feature director, and its star, the remarkable Weigert–best known for playing Calamity Jane on “Deadwood”– in her first leading film role. It helped, of course, that Rose Troche–a seasoned writer and director known best for her feature “Go Fish” and her work on the Showtime series “The L Word”–signed on to produce the film after helping Passon develop the script.

It was a classically indie shoot, filmed at Passon’s Montclair, New Jersey home with her two children playing Abby’s and Kate’s kids. Before the shoot, Weigert spent several days living with Passon and her family.“There was a lot to just sort of observe that was just right there,” she told me. “You’re stepping into a very ready-made world.”

Even with her past directing experience, Troche said she learned from Passon’s self-assured, even-handed approach: “I stood on the sidelines going, ‘oh my god, I want to do this.'” Because they were shooting on digital, Passon would leave the camera running after she called cut and just “see what [the actors] would do,” as Troche put it. Some of these un-directed, quasi-improvised moments made it into the final cut.

Weigert had no qualms about taking on a role as sexy and exposed (both physically and emotionally) as Abby. When I asked her about it, she referenced Helen Hunt’s performance as a sex therapist in “The Sessions,” and the subsequent endless questions during Q&As about Hunt’s performances during the film’s sex scenes. “You have to be in a place where you’re feeling comfortable in your own skin,” she told me. “There’s something about a woman taking her clothes off, period, that people get churned up about.”

“Concussion,” which opened this year’s LGBT-focused NewFest in New York City a few weeks ago, made a splash at Sundance this winter and was scooped up almost immediately by the Weinsteins’ RADiUS–in what was reportedly a seven-figure deal.

For Troche, it was a serendipitous case of déjà vu: her debut feature, “Go Fish,” which focused on a group of lesbian friends living in Chicago, enjoyed an almost identical trajectory at the fest almost 20 years ago. Like “Concussion,” it sold after just one screening. “It felt a little full circle to me,” Troche admits of the two films’ synchronicites.

It’s unlikely “Concussion” will be a big hit–it might well be too sexy and edgy for some audiences, although Troche plans to push for some well-deserved awards nods for Weigert’s performance and Passon’s capable directing. But even if it ends up being a lower profile film, “Concussion” feels like it’s at the leading edge of a new kind of gay cinema that focuses not on its characters ‘gayness’ but everything else in their lives that interacts with their sexuality. The stories are familiar; its the characters who are new–characters who in the past have been so categorically underrepresented.

Sometimes, as Abby learns, it takes a blow to the head to look at the things we already know through new eyes.